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Emergence of Pendular and Rotary Motions of a Centimeter-Sized Metallic Sheet under Stationary Photoirradiation

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posted on 16.01.2018, 00:00 by Yugo Harada, Keisuke Koyoshi, Hiroki Sakuta, Koichiro Sadakane, Takahiro Kenmotsu, Kenichi Yoshikawa
We report that both rhythmic pendular motion and rotary motion are generated under stationary irradiation by a green laser for a centimeter-sized metallic sheet floating on an aqueous solution. For a hammer-shaped aluminum sheet, regular pendular motion is caused by CW laser irradiation when the “handle” of the pendulum is in contact with the wall of the glass containing vessel. This rhythmic pendular motion occurs as on/off switching from a stationary state with an increase in laser power. We discuss the mechanism of such stable pendular motion in terms of limit-cycle oscillation with the aid of phenomenological coupled differential equations, by incorporating the effects of a decrease in interfacial tension with an increase in temperature under laser absorption and of the dissipation of heat into the environment. Stable rotary motion of the metallic sheet was also generated, driven by stationary laser irradiation. The chirality of the rotary motion, either clockwise or anticlockwise, for the metallic object could be selected through the introduction of chiral symmetry breaking in its morphology.

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